Water heaters are used every day in many applications. One use of water heaters is in water treatment systems wherein water containing impurities, such as excessive bicarbonate hardness, is heat-treated and filtered. Heating the water causes impurities such as bicarbonates to precipitate as solids which can be removed by filtration. However, while the heater is heating the water, calcium carbonate precipitates and deposits on the metal heating elements of the water heater and forms an insulating layer which quickly decreases the thermal conductivity and efficiency of the heating element.
Calcium carbonate deposits on metal heating elements form when a high pH of about 8.5 develops proximate the metal surface of the heating element. At this high pH, the calcium ions and carbonate ions precipitate to form solid aragonite or calcite on the metal heating element surface.
Chemical solutions have been used to overcome the problem of calcium carbonate deposits on water heater heating elements. For example, chemical solutions can decrease the hardness of water by decreasing the calcium ion concentration of the carbonate ion concentration in the water.
One use of water treatment systems is in on-premise beverage preparation (generally referred to post-mix equipment). In locations where local water supply is a health issue, on-premise water treatment is a necessity. Reliable and inexpensive water treatment systems for on-premise beverage production are desirable, but the use of chemical solutions to address the problem in beverage production is a concern. Therefore, there is a need for reducing calcium carbonate deposits on water heating elements without the use of chemical solutions, particularly in on-premise beverage production.